1. Remote Sensing Image Acquisition
Supplement to Lecture 1
material prepared by R. Lathrop 9/99
updated 8/03
includes slides previously prepared by S. Madry and C. Colvard
Readings:
ERDAS Field Guide 5th Ed. Ch 1, 3:56-82

2. Digital Image Acquisition
Digitization of analog aerial photography, can be very useful for historical studies and/or for high spatial resolution needs
Direct acquisition using some form of digital imaging sensor

3. Early attempts
Kite system acquired aerial photos of the great San Francisco earthquake and fire
Pigeon cameras
The development of aircraft
World Wars I and II

4. Aerial Cameras Keystone’s Wild RC-10 mapping camera
A large format oblique camera

5. Aerial photos Black & White - single panchromatic layer
Color: 3 layers B-G-R
Color IR: 3 layers G-R-NIR

6. USGS Aerial Photo Products
Aerial Products Description
National Aerial Photography Program (NAPP) Recent,high-quality aerial photos covering the conterminous U.S. on five- to seven-year cycles ( present).
National High Altitude Photography (NHAP) High-altitude aerial photos for the conterminous U.S. ( ).
Digital Orthophoto Quadrangles (DOQs) 
Digital images of aerial photos which combine the image characteristics of the photo with the georeferenced qualities of a map ( present).
Space Acquired Photography 
Photos taken from the International Space Station (ISS), Shuttle, Skylab, Gemini, and Apollo missions ( present).
For more info:

7. Analog Image Digitization
Scanning micro-densitometer
Linear array charge-coupled device e.g., flat-bed scanners
Area array charge-coupled device e.g., digital camera

8. Remote Sensing Systems - Instrumentation
Radiometer - electro-optical instrument measuring radiant flux (energy)
Spectroradiometer - instrument that measures radiant flux as a function of wavelength - often as a continuous spectra
Multispectral scanner - imaging spectro-radiometer measuring radiant flux in specific spectral wavebands

9. Major Elements of electro-optical scanners
Optical system: lenses, mirrors, apertures, modulators & dispersion devices
Detectors: provide an electrical signal proportional to the irradiance on its active surface, generally some type of semiconductors
Signal Processor: performing specified functions on the electrical signal to provide the desired output data

10. Electro-optical scanners
Elements sensitive to electro magnetic energy (EME) of certain wavelengths focus energy onto a sensor plane. A prism is used to divide the energy into specific wavelengths. The CCD’s are stimulated and produce an electrical signal equal to the energy focused upon it. These data are recorded.
Data are converted from an analog electrical signal to a digital number

11. 3 different scanner designs
Single detector
CCD-Scan Mirror TM
Pushbroom scanner
SPOT
Two dimensional
Staring Array
Space Imaging
Original Current Future

12. Important imaging parameters
The Instantaneous Field of View (IFOV) subtends an area on the terrain called a Ground Resolution Cell (GRC)
The Angular Field of View determines the width of the Ground Swath
The Dwell Time, the time required for the detector IFOV to sweep across the GRC

13. Airborne Remote Sensing
Aircraft Scanners Digital imagery acquired from several multispectral scanners on board NASA ER-2, NASA C-130B, and NASA Learjet aircrafts ( ).
For more info:
Digital Cameras increasingly aerial imagery is being acquired through digital camera framing systems that can collect multispectral (VIS-NIR) imagery and be quickly corrected through GPS-based navigational systems to produce digital orthophotographic imagery in near-real time

14. Remote Sensing Satellites in Space: How do they get there?

15. MODIS Terra Launches

16. Types of satellite orbits
Geostationary Polar km
35,800 km

17. Polar Orbitting Satellite

18. Geostationary vs. polar orbiting sensors
Geostationary sensors orbit with the earth continually viewing the same hemispheric area
Polar orbiters, continually view new areas of the earth as the planet rotates underneath
the sensor. Keeps the same general solar time as it cross the equator on each orbit - called sun synchronous
Polar orbit

19. Many different systems - which to choose?

20. AVHRR-Advanced Very High Resolution Radiometer
Polar orbit, coarse spatial resolution: 1 and 4 km cells, broad 2400 km ground swath width
2 operational now-1 day and 1 night pass for each

21. AVHRR Thermal AVHRR provides water temperature data 3 bands in TIR
Gulf Stream

22. Remote Sensing of the Earth: Clues to a Living Planet
Scientists at the NASA Goddard Space Flight Center have used the AVHRR to create maps of vegetation greenness for the entire globe
The NASA scientists have combined numbers of satellite images to create a composite picture of the earth at approximately biweekly intervals over a number of years
For more info and images, go to:

23. Global AVHRR composite
1 band in the Red: um
1 band in the NIR: um
Vegetation Index to map vegetation amount and productivity

24. Remote Sensing of the Earth: Clues to a Living Planet
You can access these images over the INTERNET
You can either browse through individual images or watch an animation
First, click on the Global 1 degree 1986 NDVI (Climate Data Set) (1.5 MB Quicktime) animation. Open it, and click on the > button. You can go more slowly by clicking on the |> button.

25. Remote Sensing of the Earth: Clues to a Living Planet
First, click on the Global 1 degree 1986 NDVI (Climate Data Set) (1.5 MB Quicktime) animation. Open it, and click on the > button.
Watch closely, can you observe the Green Wave in the northern hemisphere?
What about the Brown Wave?
Now look at the southern hemisphere. What do you observe?

26. Can you see the Green Wave?

27. Remote Sensing of the Earth: Clues to a Living Planet
Now take a look at the Northern hemisphere in greater detail.
Click on the North America 1986 NDVI (750K quicktime) Animation.
Can you find where you live? How long does it stay green?
Compare Florida with Maine or Minnesota.

28. North America: Close-up

29. Remote Sensing of the Earth: Clues to a Living Planet
To access more recently acquired AVHRR imagery go to the National Oceanographic & Atmospheric Administration (NOAA) Satellite Active Archive

30. After a picture-perfect launch into space December 1999, Terra
Began releasing images April Terra includes MODIS, a 2nd generation “AVHRR-like” instrument, with a number of potential applications in regional to global scale environmental monitoring of the land, ocean and atmosphere. Also includes ASTER, CERES, MISR and MOPITT.
For more info go to:

31. MODIS TERRA in Orbit

32. 36 discrete bands between 0.4 and 14.5 µm
spatial resolutions of 250, 500, or 1,000 m at nadir.
Signal-to-noise ratios are greater than 500 at 1-km resolution (at a solar zenith angle of 70°), and absolute irradiance accuracies are < ±5% from 0.4 to 3 µm (2% relative to the sun) and 1 percent or better in the thermal infrared (3.7 to 14.5 µm).
MODIS instruments will provide daylight reflection and day/night emission spectral imaging of any point on the Earth at least every 2 days, operating continuously.
For more info:

33. 3 visible/NIR(VNIR: 0.5 and 0.9 µm) with 15-m resolution
3 mid IR (SWIR: 1.6 and 2.43 µm) with 30-m res.
5 TIR (8 and 12 µm) with 90-m resolution
60- km swath whose center is pointable cross-track ±8.55° in the SWIR and TIR, with the VNIR pointable out to ±24°. An additional VNIR telescope (aft pointing) covers the wavelength range of Channel 3. By combining these data with those for Channel 3, stereo views can be created, with a base-to-height ratio of 0.6.
Overpass every 16 days in all 14 bands and once every 5 days in the three VNIR channels. For more info:

34. “Aqua,” Latin for “water,” is a NASA Earth Science satellite mission named for the large amount of information that the mission will be collecting about the Earth’s water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice.
Additional variables also being measured by Aqua include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures. The AQUA Platform includes the MODIS, CERES and AMSR_E instruments. Aqua was formerly named EOS PM, signifying its afternoon equatorial crossing time. AQUA was launched May For more info:

35. ERTS-1 Earth Resources Technology Satellite-1
Renamed Landsat Multispectral scanner (MSS)
First images in late 1972
Was the first civil remote sensing satellite

36. Landsat MSS bands 4 and 5
GREEN
RED

37. Landsat MSS bands 6 and 7 INFRARED 1 INFRARED 2
Note: water absorbs IR energy-no return=black
INFRARED 1
INFRARED 2

38. MSS color composite combining bands creates a false color composite
Manhattan
Rutgers
combining bands creates a false color composite
red=vegetation
light blue=urban
black=water
pink=agriculture
Philadelphia
Pine barrens
Chesapeake
Bay
Delaware River

39. Landsat 4-5 Thematic Mapper (TM)

40. Cross-track scanning system

41. Landsat TM-7 bands-8 bit data
Spectral
(where we look)
Radiometric
(how finely can we
measure the return)
0-63, 0-255,
Landsat TM BAND

42. Spectral wavebands of Landsat TM

43. Landsat TM: each waveband provides different information about earth surface features

44. Thermal imagery-temperature
Water analysis-nuclear power cooling ponds)

46. Commercialization of Landsat
Landsat was commercialized by Pres. Reagan
EOSAT formed
sales dropped

47. Landsat 7 15 m ETM+ (enhanced TM) sensor April 1999 launch
Oct.’92 Land remote sensing policy act
a panchromatic band with 15m spatial resolution-fully coregistered w/30m
on-board, full aperture, 5% absolute radiometric calibration
a thermal IR channel with 60m spatial resolution
for more info go to:

50. Will have 2.5 m in 1999 French commercial remote sensing system
First launch in 1986
10 and 20 m spatial resolution
60 km swath width
Stereo viewing ability
Will have 2.5 m in 1999

51. Panchromatic (PAN) sensor: 10 m GRC
Pan um
High Resolution Visible (HRV) sensor: 20m GRC
G (.5-.59), R ( ), NIR ( )
Ground Swath Width of 60 km
For more info go to:

52. SPOT before launch

53. SPOT ground stations

54. SPOT 4 1st images taken March 31, 1998

55. Polar Sun synchronous orbit
2 side-by-side HRV sensors

56. SPOT has steerable mirror

57. Stereo imaging

58. Indian Remote Sensing (IRS) satellite
IRS-1C launched in December 1995
IRS1D launched in September 1997
Panchromatic: um
5.8 m GRC, 30 km ground swath
22 day repeat cycle with off-nadir pointability

59. Space Imaging IKONOS Panchromatic (045-0.9 um): 1 m
Multispectral: 4 m Blue ( nm), Green( nm) Red ( nm) NIR ( nm)
11 km swath width
Pointable to 45o for daily viewing
For more info go to:

60. IKONOS SAMPLE IMAGERY
Multi-spectral
4m GRC
Pan-chromatic
1m GRC

61. Space Imaging IKONOS Imagery Sample: Bound Brook NJ
1 m panchromatic
4 m multi-spectral

62. OrbView-3
Panchromatic: 1 m
Multispectral (color): 4 m
Pointable: anywhere on globe within 3 days
Additional hyperspectral sensor
For more info go to:

64. Quickbird
DigitalGlobe™ successfully launched its QuickBird satellite on the Boeing Delta II launch vehicle on October 18, 2001.
Panchromatic: m
Multispectral (color): m
Can increase the resolution system by adjusting the orbit in which the satellite is flown. As a result, panchromatic resolution increases from 1 meter to 61 centimeters and multi-spectral increases from 4- to 2.5-meter resolution.
The satellite will operate in a 450-km 98-degree sun-synchronous orbit, with each orbit taking 93.4 minutes

65. Different sensors and resolutions
sensor spatial spectral radiometric temporal
AVHRR and 4 KM or 5 bands bit hours
2400 Km , , (0-1023) (1 day, 1 night)
, (micrometers)
Landsat MSS meters bands bit days
185 Km , .6-.7, .7-.8, (0-63)
Landsat TM 30 meters bands bit days
185 Km , , , (0-255)
.76-.9, ,
, um
SPOT P meters band bit days
60 Km um (0-255) (2 out of 5)
SPOT X meters bands bit days
60 Km , , um (0-255) (2 out of 5)
IKONOS and 4 meters and 4 bands bit days
11 km , , , (0-1023) ,

66. Homework 1: Selecting and Ordering Imagery
1. Enhanced Landsat Thematic Mapper 7 (ETM+) imagery is available through the U.S. Geological Survey. Go to the USGS’ Earth Explorer web site ( or their newer, better web browser (
A. How many Landsat TM scenes are needed to image the entire state of New Jersey?
B. What are the Path/Row numbers?
C. What is the cost per square km for the ETM+ Level 1G image?
Hint: 1st determine the area of the scene in km2, then divide scene cost by area
D. Using the Search Archive capabilities, determine the date of the most recent cloud-free (<20%) ETM+ image for Middlesex County, NJ. What is the Scene ID, Path/Row and date?

67. Homework 1: Selecting and Ordering Imagery
2. The OrbImage Corporation ( markets OrbView and other high resolution imagery. Access the OrbImage site to get up-to-date information on pricing and availability.
A. What is the spatial accuracy and cost per square kilometer for the standard OrbView Cities product? OrbView Cities Plus?
3. DigitalGlobe ( markets Quickbird imagery. Access the DigitalGlobe site to get up-to-date information on pricing and availability?
A. What types of Quickbird image products are offered?

68. Good Bye from Planet Earth
Source